UPDATE 2-Banks lead FTSE 100's descent; Thomas Cook collapse buoys rivals

* FTSE 100 down 0.3%, FTSE 250 slips 0.6%

* Banks, miners lead fall

* Thomas Cook collapse boosts shares in rivals

* Marks & Spencer falls on mid-cap index
(Adds news items, analyst comments, updates to close)

By Yadarisa Shabong and Indranil Sarkar

Sept 23 (Reuters) - London's FTSE 100 index slipped on
Monday as weak German economic data weighed on banking shares,
offsetting a surge in travel operators and airlines after the
collapse of the world's oldest travel firm Thomas Cook.

The FTSE 100 fell 0.3% with financials and mining
stocks dragging the most, while the FTSE 250 midcaps index
shed 0.6%.

The banking index lost nearly 1%, tracking a
fall in British bond yields, after weaker-than-expected German
data showed the private sector contracting for the first time in
more than six years.

Further dampening sentiment in the sector was a note by
JPMorgan saying it expects downward risks for UK domestic banks
in most Brexit scenarios.

Global miners such as Glencore and Antofagasta
also weakened as a lack of clarity in U.S.-China trade
talks dented metals prices.

"Trade tensions between the two largest economies in the
world are having an impact around the global, and the dreadful
manufacturing figures from Germany this morning is a great
example of how the problem spills out beyond the U.S. and
China," CMC Markets analyst David Madden said.

The FTSE 100, whose constituents bring in more than
two-thirds of their profits from abroad, saw its steepest
monthly fall this year in August when trade tensions between the
United States and China escalated.

While the index has benefited from the weakness in the pound
for most of 2019 as a painful Brexit process plays out, recent
steps by lawmakers in preventing a no-deal Brexit have brought
gains for the currency and in turn weighed on exporters.

The FTSE 100 has gained just 8.9% so far in the year, well
behind its European counterpart's 15.4% rise.

The collapse of Thomas Cook spurred buying in tour operator
TUI, airlines Ryanair and easyJet and
British Airways owner IAG, as investors anticipated the
tour operator's closure would cut capacity in the saturated
European holiday market.

"Such a tragic collapse… leaves plenty of money on the table
for its sector peers, a fact that hasn't gone unnoticed by
investors," Spreadex analyst Connor Campbell said.

The FTSE 350 travel and leisure index rose to
its highest level in almost a year.

Marks & Spencer lost 3.2%, on its first day as a
mid-cap constituent and after the abrupt departure of its
finance chief on Saturday.

It is the first time the 135-year old retailer has been
relegated from the FTSE 100 since the index's inception in 1984.

(Reporting by Yadarisa Shabong, Indranil Sarkar, Muvija M and
Shashwat Awasthi in Bengaluru; editing by Patrick Graham,
Saumyadeb Chakrabarty and Kirsten Donovan)